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US 4,220,816 AGranted
Digital duplex transmission system
AssigneeInternational Standard Electric Corporation
InventorsGeorge A. Howells, James A. Murray, Douglas E. Woodman
Life of this patent
Estimating the term…
Abstract
A digital duplex transmission system for use in a local area uses a modified dipulse code from the exchange terminal to the subscriber terminal and either a different modified dipulse code or a modified AMI (Alternate Mark Inversion) code in the other direction to achieve time separation of signals at each terminal. Incorporation of a hybrid separator in each terminal further improves the performance of the system.
Claims9
A digital duplex transmission system comprising:
- two terminals interconnected by a 2-wire transmission line;
- first means disposed in one of said terminals coupled to said line for transmitting isochronous digital signals as pulse encoded signals of one type having a duty factor not exceeding 50% over said line;
- second means disposed in the other of said terminals coupled to said line for transmitting isochronous digital signals as pulse encoded signals of a different type having a duty factor not exceeding 50% over said line;
- said one type of encoded signals and said different type of encoded signals having the same digit repetition rate;
- third means disposed in said one of said terminals coupled to said line to receive said different type of encoded signals from said line;
- and
- fourth means disposed in said other of said terminals coupled to said line to receive said one type of encoded signals from said line;
- the timing of one of said one type of encoded signals and said different type of encoded signal transmitted from one of said one of said terminals and said other of said terminals having a predetermined fixed relationship with the other of said one type of encoded signals and said different type of encoded signals received at said one of said one of said terminals and said other of said terminals such that the periods of zero signal in said one of said one type of encoded signals and said different type of encoded signals coincide with the significant portions of said other of said one type of encoded signals and said different type of encoded signals.
5 more elements
Dependencies are inferred from the claim text.